The expression of HA protein by rAPMV-3 or rNDV and incorporation of HA protein into rAPMV-3 or rNDV particles. The monolayer of DF1 cells were infected with rNDV, rNDV/HA or rAPMV-3/HA at 0.1 MOI. The cell lysates were collected 30 hours after infection. The expression of HA protein was detected by Western blot analysis using a polyclonal chicken anti H5N1 serum. (A) Lanes 1–4 represents; DF1 cells, rNDV, rAPMV-3 HA and rNDV/HA, respectively. The recombinant viruses were inoculated in 10-day-embryonated SPF chicken eggs, the infected allantoic fluids were collected three days post-inoculation and were partially purified. The incorporation of HA protein into rAPMV-3 or rNDV particles were detected by Western blot analysis using the mentioned serum. (B) The lanes 1–4 represent; rNDV, rNDV/HA, empty lane and rAPMV-3/HA, respectively. The full-length gels are presented in Supplementary Fig. S1.